Both hepatitis B and D viruses are diagnosed by blood tests. The incubation period for hepatitis B from exposure to clinical symptoms ranges from 60 to 180 days, and blood tests may not reveal the infection for four weeks or more. Eight separate assays can determine the stage of hepatitis B. Fortunately, only one blood sample is needed and all assays can be performed from the same sample.
Physical examination of patients with hepatitis B may reveal swollen lymph nodes in the neck and enlargement of the spleen and liver. Liver enlargement may be minimal with slight tenderness when a physician feels the liver. In some patients, however, a physical examination reveals nothing.
A liver biopsy is generally not necessary but may be considered if the physician is uncertain of the diagnosis. A biopsy should be performed if there are atypical symptoms of the disease or the symptoms are quite prolonged. If clues of chronic liver disease are present, such as an enlarged spleen, or if there are complications such as swelling of the brain or diffused bleeding, a liver biopsy may be necessary.
This section contains more information on what doctors look for in blood tests.
A patient who has an acute hepatitis B infection is diagnosed when a specific marker, or antigen, is found during the blood test. The antigen denotes the presence of an active, hepatitis B infection. The tests may remain positive throughout the early phases of the illness.
Chronic hepatitis B infection is diagnosed when the presence of the antigen is found for more than six months. In a small number of patients who have the infection, the marker is not found during the blood tests. In those rare cases, doctors use blood tests that look for hepatitis B DNA to diagnose chronic infection. These patients have mutant type of hepatitis B, which may be associated with progressive liver disease.
Serum enzymes, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), are a sensitive tool for establishing a diagnosis of viral hepatitis. ALT and AST are the first enzymes to reveal abnormalities during the disease process and the last to normalize. They may reach levels 100 times the upper limits of normal during the acute infection. ALT is usually more abnormal than AST in the early and late stages of the disease.
Serum bilirubin—a byproduct of old red blood cells normally processed and removed from the bloodstream by the liver—at levels of 2.5 to 3.0 milligrams per deciliter or greater establishes the presence of the jaundice phase of hepatitis.
Last reviewed on 7/23/09
U.S. News's featured content providers were not involved in the selection of advertisers appearing on this website, and the placement of such advertisement in no way implies that these content providers endorse the products and services advertised. Disclaimer and a note about your health.